Mars Express starts unfurling radar booms

Over the next two weeks the European Space Agency's Mars Express orbiter will deploy its radar booms and start looking up to 5km below the Martian surface for water, and other materials.

Deployment of the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument) instrument has been delayed for over a year, because of fears that the booms could damage the orbiter. In early 2004 the boom's manufacturers said that new simulations suggested that the booms could over-extend when their pyro technics fired, putting the craft's delicate instruments at risk.

Following testing by NASA engineers at the JPL laboratory, mission scientists finally got the go-ahead to deploy in February this year.

The MARSIS instrument comprises three arms - or booms - and each will be deployed separately. Before each phase, the spacecraft will be placed in what ESA describes as "robust" attitude control mode. This means the craft will be able to spin freely in space while the boom is extended.

The two 20-metre dipole booms which make up MARSIS's main antenna will be set up first and if all goes well will be followed by the seven-metre, receive-only, monopole boom. After each boom is unfurled, ESA says it will carry out a full assessment of the craft before moving on to the next phase.

According to the current schedule, all three booms should be up and running by 12 May. However, ESA says this is very much subject to change.

In related news, NASA's next robotic emissary to Mars arrived in Florida yesterday to begin final testing ahead of its August launch.

The Mars Reconnaissance Orbiter (MRO) will study the composition and structure of Mars' atmosphere and sub-surface, NASA says. It will also be on the look out for sites for future Martian landings, and will serve as a high-data-rate communications relay for surface missions. ®